Different techniques are used to automate complex biological protocols, such as the preparation and extraction of DNA from a sample of a few millimeters. In all cases, the presence of several reagents requires the existence of different storage chambers and at least one reaction chamber. Means enabling the movement of the fluids are also necessary.
A first known device, used in particular by Genpoint and implementing a preparation robot marketed by Tecan, comprises means for three-dimensional movement of a pipette and a plate having a plurality of wells, the wells containing either a reagent or a sample.
The pipette is moved above the plate so as to be positioned in a well in order to withdraw a quantity of reagent, then positioned in the well containing the sample in order to deliver the quantity of reagent into that well, successively for each reagent.
Additional means necessary for the progression of the reactions, in particular heating or magnetic capture means (magnetic sedimentation of suspended particles), can be arranged under the plate.
Such a device has the drawback of using mechanical precision means to move the pipette, which are complex and difficult to transport.
Furthermore, such a device comprises open wells, in which contaminations between wells can occur.
In order to limit these contaminations, it has in particular been contemplated to use single-use pipette cones, possibly cottoned to prevent contaminations in aerosol form, to provide means for washing the sampling needles, to prevent contaminations by contact, or to place reagents in single-use closed consumable containers. Thus, in certain devices comparable to pipetting robots, the reagents are placed in single-use consumables that are only opened at the time of the test. In particular, the VIDAS® system, marketed by bioMérieux, comprises such a device. However, the chamber containing the reaction space is still exposed to the open air, leading to possible aerosol contaminations. There are also well plates comprising reservoirs closed by membrane seals or septa. These reservoirs are distributed over a same plane. The movement of the sampling head is therefore done along three axes.
To prevent contaminations between tests, it has therefore been considered to produce unitary tests in hermetic single-use devices.
Thus, documents U.S. Pat. Nos. 6,878,540, 6,440,725, and 6,881,541 describe devices including a single-use cartridge comprising an assembly of chambers or reservoirs intended to receive in particular a sample, wash fluids, elution fluids, reagents, the chambers or reservoirs being connected by a set of channels. These devices also comprise a microfluidic chip. The movement of the fluids between the different chambers and reservoirs is ensured via the set of channels under the effect of pumps and flow control means of the valve or fluidic diode type. One use of these devices is the performance of the treatment of a fluid sample to extract and amplify nucleic acids, in particular by PCR.
Document U.S. Pat. No. 6,374,684 also describes a single-use cartridge comprising a set of chambers and reservoirs. In the case of this document, a single treatment chamber is used, which can be placed in fluid communication with other chambers or reservoirs selectively via channels formed in a rotary member.
These solutions make it possible to effectively decrease contaminations, but involve placing a fluid communication and movement structure between the chambers, which remains complex.
Document U.S. Pat. No. 6,964,862 describes a device comprising a single-use element having chambers separated by walls allowing a fluid communication above a predetermined pressure. Each chamber is filled with a specific fluid before closing. Placing the fluids contained in two adjacent chambers in communication is done via mechanical pressure on one of the two chambers, which causes an opening to appear in the separating wall.
This device makes it possible to simplify the realization of the communication between the chambers, and also makes it possible to limit contamination between tests. It does, however, have the drawback of having to make a sequential and irreversible use of the chambers.
Document WO95/21382 describes a device comprising a single-use element having a first chamber, a second chamber, and a third chamber aligned in that order and separated by polymer walls. Suction means are connected to the space of the second chamber. A needle delimiting an inner cavity comprising two openings situated at the two ends of the inner cavity can be moved so as to produce communication between the first chamber and the second, or between the second chamber and the third.
This device requires that the chambers be used in a predetermined order with an imposed movement of the fluid towards the second chamber and is limited to a use of three chambers. The use of the chambers is also irreversible.